The work is directed at determining the mechanism by which extracellular (K ion) augments protein synthesis in cerebral tissue and at determining the functional significance of this effect. We shall examine the effect of the Ca 2 ion ionophore, A23187, in combination with altered extracellular (K ion) upon protein synthesis to determine whether the effect of extracellular (K ion) and depolarizing agents upon intracellular ion concentration of non-cerebral tissue (or white matter) and upon membrane potentials of hippocampal neurons to determine whether the effect is mediated by increased intracellular K ion/Na ion or whether it is mediated by changes in membrane potential. We shall carry out studies of the effect of changes of extracellular (K ion) on protein synthesis of the in situ cortex to see if the effect is manifested in situ. We shall carry out separation of neuronal and glial elements of the hippocampus to determine the cell type in which extracellular (K ion) activates synthesis. We shall carry out a complete subcellular fractionation of the tissue to determine in which cellular elements protein synthesis is activated by extracellular (K ion).